The Stovebolt Site Forums The Shop Area Engine Shop Steering Caster Angle

If I drop the front end of my 1/2 ton an inch and a half or two inches by using smaller diameter wheels and lower profile tires, will I be upsetting the caster angle on the steering enough to affect straight-line driveability?

The change in caster should be very small for a 1.5" drop. If you really want to calculate it, look up the sine angle of 1.5 (your maximum front drop) divided by 116 (your wheelbase in inches)which is gives an answer of .0129 which gives a reduction in caster of about 45 minutes of arc or 3/4 of a degree in plain english.

Stuart.

If you are putting smaller diameter wheel and tires on the caster angle should not change.

I read Chevypanel52 post as a query on dropping the front end only by using a smaller diameter wheel/tyre setup, so the caster would change slightly. If his query was about dropping both ends by the same amount it wouldn't change as you say.

Stuart.

Don, smaller tires will change the caster. If you think about the axle and how its mounted to the springs, the king pins are angled back so the truck will track straight. The angle is set with the truck setting a few degrees lower in the front. When you change tires, the front is now much lower so the king pins are not nearly as angled back as they were, so you have to add more shim to get the king pins back where they were originally.

The way I understand it is, the king pins always have to stay at the same angle in relation to the road surface, so if the truck is lowered in front or raised in the rear, you have to maintain the king pin angle.

Joe

Sorry bout that. I wasn't thinking about only lowering the front by putting a smaller tire/wheel combo on. I appreciate pointing it out. Thanks

I'm thinking if You lower the front end and keep the rear at stock ht. You'll be increasing the caster silghtly not decreasing because the truck is angled down from back to front.

Pete

The positive caster that an AD truck has means that the kingpins lean backwards slightly when they're viewed from the side of the truck, so dropping the front end would make them slightly more upright and so reduce the positive caster slightly. The amount of reduction will be about 3/4 of a degree for 1 1/2" of front drop.

Stuart.

You're right ,Stuart,looked at the manual again and realized My mistake,Thanks.

Pete

Thanks for all the input on that, if and when I get the wheels & tires, I'll get the front end set-up properly.
Is anybody running Wheel Vintique rims on their AD Chevy Trucks? I can't seem to get an answer from the company on whether their Series 12 Smoothies will fit or not. I know the center bore on their 16 inch 6 lug rims is 4.25", don't know if this is too big, the stock rims measure 3.75"

I don't know about the Vintique wheels, but mine are the reproduction Chevrolet Ralley wheels bought from a swapmeet vender. The center bore is way bigger then the hubs, and the lug nuts are used to center the wheel on the hubs. It works OK, all mine run true and even, and after 9000 miles they are still going.

Joe